On Thursday, May 5, 2016, at around 11:56 Japan Standard Time (JST: UTC + 9 hours a privately owned Glasflügel 304CZ-17, registered JA21BB (glider, single seater), took off from the Kakuda Glider Field in Kakuda City, Miyagi

Prefecture by aero tow for a training flight, but crashed in a mountain forest in Miharu Town, Tamura-Gun, Fukushima Prefecture at around 14:05.

The pilot was the only person on board the aircraft, and he was fatally injured. The glider was destroyed.

Probable Causes:

It is highly probable that this accident occurred when JA21BB crashed in a mountain forest because it broke up in mid-air while flying.

It is somewhat likely that the glider broke up in mid-air because, after it had entered a steep turn and stalled while the pilot had succumbed to a state of hypoxia and was semi-conscious, excessive bending occurred owing to aerodynamic force on the glider and the glider was subjected to load exceeding the ultimate maneuvering load, influenced by the fact that the glider assumed a significant nose-down attitude including spin and nosedived, and that it passed through an area of turbulence.

It is somewhat likely that the pilot succumbed to a state of hypoxia because he had forgotten to open the oxygen valve before setting off and thus started the flight with no supply of oxygen, and had not noticed that oxygen was not being supplied because he did not check the oxygen supply during flight, and so continued to climb without noticing signs of hypoxia in himself.